Method and system to reduce wireless network packets for centralised layer two network

ABSTRACT

A method of operating a communication system, comprising the steps of: receiving a first OSI layer two packet from a first network interface; determining transmission type of the first OSI layer two packet; determining whether to send a second OSI layer two packet according to the transmission type, origin and destination of the first OSI layer two packet; determining destination address and transmission type of the second OSI layer two packet when determined to send the second OSI layer two packet; and sending the second OSI layer two packet through a second network interface when determined to send the second OSI layer two packet; wherein when the first OSI layer two packet is encapsulated in at least one layer three packet, the second OSI layer two packet is not encapsulated in any OSI layer three packet; and wherein when the first OSI layer two packet is not encapsulated in any Open Systems Interconnection (OSI) layer three packet, the second OSI layer two packet is encapsulated in at least one OSI layer three packet.

SUMMARY

A communication system capable of establishing and terminating at least one layer two tunnel, such as a VPN established by using Layer Two Tunnelling Protocol (L2TP), reduces broadcast or multicast packets by converting a first layer two packet from broadcast or multicast to a unicast layer two packet and convert a unicast layer two packet to a broadcast or multicast packet. The communication system determines whether to conduct the conversion according to the transmission type, origin of the first layer two packet or destination of the first layer two packet. According to one of the embodiments of the present invention, the communication system may determine not to send the broadcast or multicast layer two packet.

According to one of the embodiments of the present invention, the communication system learns the destination address of the unicast layer two packet by exchanging User Data Protocol (UDP) packets at a pre-defined port number. The communication system intercepts any UDP packets arriving at the specific UDP port and checks the payload of the UDP packets. If the payload matches a pre-defined format or content, the communication system is then able to recognize the layer two and layer three addresses of the sender of the UDP packet as the address for the layer two unicast destination address.

BACKGROUND ART

The use of wireless network communication systems that permit hosts to communicate via an optical cable, copper cable, or radio link has become widespread. Hosts are embedded with wireless communication electronics to communicate with other hosts and also to connect to a core network via access points, such as a local area network (LAN) and the Internet. The access point relays network packets between hosts and the core network, and also among hosts.

Hosts and base stations using Open Systems Interconnection (OSI) layer two technologies, such as Ethernet, to communicate with the core network and each other are less efficient at handling broadcast and multicast network packets. One kind of broadcast network packets on Internet Protocol (IP) networks belongs to Address Resolution Protocol (ARP) protocol network packets. For multicast network packets, the Internet Group Management Protocol (IGMP) is one of many communications protocol used by hosts and adjacent routers to establish multicast group memberships.

Due to historical technology development, hosts that belong to the same layer two networks are usually close together and share the same communication channel or the cost of communications with each other is low. Therefore, broadcast and multicast packets in layer two networks have not been a significant concern. When a layer two network is formed through layer three networks, broadcast and multicast packets in the layer two network may become a concern as the amount of packets increases. ARP proxy, proxy server, LAN segmentation, caching are common methods to reduce layer two broadcast and multicast packets.

When layer two packets are encapsulated in layer three packets, for example through Layer Two Tunnelling Protocol (L2TP) and virtual private network (VPN), the amount of broadcast and multicast packets could have a severe negative impact on layer three network performance. Furthermore, when radio spectrum is used to transmit the layer three packets, there may not be enough capacity to transit the broadcast and multicast packets.

Prior arts ARP proxy, proxy server, LAN segmentation, caching and other broadcast and multicast packets reduction techniques do not allow transmission of broadcast and multicast packets selectively and particularly broadcast and multicast packets originated from a mobile network device through layer three networks.

U.S. Pat. No. 7,356,032 discloses a system and method for reducing broadcast packets among mobile units by using a cache to store Ethernet/IP address pairs in each base station. However, U.S. Pat. No. 7,356,032 cannot reduce broadcast packets if the mobile units are connecting to the core network using OSI layer two protocol through layer three networks. Also U.S. Pat. No. 7,356,032 relies on wireless access point to manage ARP packets. This also increases the complexity of the design of wireless access point.

FIG. 1 illustrates a network environment where communication systems and hosts, such as client computers 111, 112, 113 and 114, communicate to wide area networks (WANs) or the Internet directly. In this particular network environment, those skilled in the art would appreciate that when client computer 111 sends OSI layer three packets to the Internet through the following steps: first, client computer 111 sends OSI layer three packets to wireless access point (AP) 101 (Computer Layer Two Packets) through radio link 121, wherein the layer two packets encapsulate layer three packets from computer 111 (Computer Layer Three Packets); secondly, AP 101 communicates with Tunnel Termination Gateway 104 through interconnected networks, such as Internet 103, by using layer three packets (AP Layer Three Packets) to encapsulate Computer Layer Two Packets; thirdly, Tunnel Termination Gateway 104 decapsulates AP Layer Three Packets to retrieve Computer Layer Two Packets and sends Computer Layer Two Packets to Internet Gateway 106 through private networks 105; finally, Internet Gateway 106 decapsulates Computer Layer Two Packets to retrieve Computer Layer Three Packets and sends Computer Layer Three Packets to Internet 103.

When there are OSI layer three packets for client computer 111 from Internet 103: first, Internet Gateway 106 receives the layer three packets (Internet Packets) from Internet 103 and sends the Internet Packet to Tunnel Termination Gateway 104 by encapsulating Internet Packet in layer two packets (Gateway Layer Two Packets); secondly, Tunnel Termination Gateway 104 encapsulates Gateway Layer Two Packets in layer three packets (Tunneled Layer Three Packets) and sends Tunneled Layer Three Packets to AP 101 through Internet 103; thirdly AP 101 decapsulates Tunnelled Layer Three Packets to retrieve Gateway Layer Two Packets and sends Gateway Layer Two Packets to client computer 111 through radio link 121; finally client computer 111 retrieves Internet Packets by decapsulating Internet Packets from Gateway Layer Two Packets.

AP 101 and Tunnel Termination Gateway 104 are connected through a layer two tunnel by using layer three packets. The layer two tunnel may be implemented by using L2TP or other tunnelling protocols. Myriad other combinations and permutations of how to establish a layer two tunnel between two communication systems using layer three packets would be appreciated by those of ordinary skill given the present disclosure.

The steps of communicating with Internet 103 by client computer 112 are similar to the steps of communicating with Internet 103 by client computer 111. The same steps are applied to computing devices 113 and 114, however instead of using AP 101, AP 102 is used. It is apparent to a skilled person in the art how the steps of communicating with Internet 103 also apply to hosts, client computers, computing devices and communication systems through wireless access points, Tunnel Termination Gateway 104, private networks 105 and Internet Gateway 106.

It may be noted that server 115 and client computers 111, 112, 113 and 114 all belong to the same layer two network as they are connected through layer three networks between AP 101 and Tunnel Termination Gateway 104 and between AP 102 and Tunnel Termination Gateway 104. Therefore, when server 115 sends a layer two broadcast or multicast packet, the broadcast or multicast packet is then duplicated by Tunnel Termination Gateway 104, AP 101 and AP 102 and sent to client computers 111, 112, 113 and 114. This type of broadcast or multicast network packets may easily consume a significant part of network resources between AP 101 and Internet 103, between AP 102 and Internet 103, between Tunnel Termination Gateway 104 and Internet 103, radio spectrum of AP 101 and radio spectrum AP 102. This invention aims to reduce broadcast and multicast network packets in the network environment just described.

DISCLOSURE OF INVENTION

The ensuing description provides preferred exemplary embodiment(s) only, and is not intended to limit the scope, applicability or configuration of the invention. Rather, the ensuing description of the preferred exemplary embodiment(s) will provide those skilled in the art with an enabling description for implementing a preferred exemplary embodiment of the invention. It is understood that various changes may be made in the function and arrangement of elements without departing from the spirit and scope of the invention as set forth in the appended claims.

Specific details are given in the following description to provide a thorough understanding of the embodiments. However, it will be understood by one of ordinary skill in the art that the embodiments may be practiced without these specific details. For example, circuits may be shown in block diagrams in order not to obscure the embodiments in unnecessary detail. In other instances, well-known circuits, processes, algorithms, structures, and techniques may be shown without unnecessary detail in order to avoid obscuring the embodiments.

Also, it is noted that the embodiments may be described as a process which is depicted as a flowchart, a flow diagram, a data flow diagram, a structure diagram, or a block diagram. Although a flowchart may describe the operations as a sequential process, many of the operations may be performed in parallel or concurrently. In addition, the order of the operations may be re-arranged. A process is terminated when its operations are completed, but could have additional steps not included in the figure. A process may refer to a method, a function, a procedure, a subroutine, a subprogram, etc. When a process corresponds to a function, its termination corresponds to a return of the function to the calling function or the main function.

Moreover, as disclosed herein, the term “computer storage medium” may represent one or more devices for storing data, including read only memory (ROM), random access memory (RAM), magnetic RAM, core memory, magnetic disk storage mediums, optical storage mediums, flash memory devices and/or other machine readable mediums for storing information. The term “machine-readable medium” includes, but is not limited to portable or fixed storage devices, optical storage devices, wireless channels and various other mediums capable of storing, containing or carrying instruction(s) and/or data.

Furthermore, embodiments may be implemented by hardware, software, firmware, middleware, microcode, hardware description languages, or any combination thereof. When implemented in software, firmware, middleware or microcode, the program code or code segments to perform the necessary tasks may be stored in a machine readable medium such as computer storage medium. A processing unit(s) may perform the necessary tasks. A code segment may represent a procedure, a function, a subprogram, a program, a routine, a subroutine, a module, a software package, a class, or any combination of instructions, data structures, or program statements. A code segment may be coupled to another code segment or a hardware circuit by passing and/or receiving information, data, arguments, parameters, or memory contents. Information, arguments, parameters, data, etc. may be passed, forwarded, or transmitted via any suitable means including memory sharing, message passing, token passing, network transmission, etc.

A network interface, such as LAN interface and WAN interface, that may be provided by the communication system (CS) is an Ethernet interface, a frame relay interface, an antenna interface, a fibre optic interface, a cable interface, a DSL interface, a token ring interface, a serial bus interface, an universal serial bus (USB) interface, Firewire interface, Peripheral Component Interconnect (PCI) interface, etc. In one variant, a network interface is in a processing unit and therefore the agent for connecting with optical fiber, cables or antenna may directly connect with the processing unit. In one variant, a network interface may connect to a Wi-Fi adapter for Wi-Fi network connection. In one variant, a network interface may connect to a USB port and the USB port may connect to an external modem for wireless WAN connection, such as a USB 3G modem, USB LTE modem, USB WiMAX Modem, USB Wi-Fi Modem, or other modem for wireless communications. Myriad other combinations and permutations of the foregoing will be appreciated by those of ordinary skill given the present disclosure.

In order to improve readability, Open Systems Interconnection (OSI) layer two is interchangeable in this present invention with layer two and similarly OSI layer three is interchangeable with layer two.

A base station, interchangeable in this present invention with access point, is a radio receiver/transmitter that serves as the hub of the local wireless network, and may also be the gateway between a wired network and the wireless network. It may consist of a transmitter and wireless router.

A host is an electronic device, such as a mobile phone, computer, server, router, switch, sensor and etc, connected to a computer network. A host may offer information resources, services, and applications to users or other nodes on the network. A host is a network node that is assigned a network layer host address. Hosts may have one or more Internet Protocol (IP) addresses assigned to their network interfaces. The addresses are configured either manually by an administrator, automatically at start-up by means of the Dynamic Host Configuration Protocol (DHCP), or by stateless address auto-configuration methods.

A pre-defined layer two broadcast destination address is an address known to the CS as a broadcast address, including Ethernet broadcast address FF:FF:FF:FF:FF:FF in hexadecimal, an address used by CS manufacturer for proprietary broadcasting and an address configured by the administrator of the CS manufacturer for proprietary broadcasting. A multicast destination address is an address known to the CS as a multicast address, including multicast address learnt by the CS through IGMP.

A CS is a host capable of establishing and terminating at least one layer two tunnel, such as a VPN established by using L2TP, receiving layer two packets, and sending layer two packets. As the CS has to be able to establish and terminate at least one layer two tunnel, the CS has to able to receive and send layer three packets. The CS may communicate to other hosts through wireless and/or wired networks. The CS may be an 802.11 access point capable of handling IEEE 802.11 protocol. The CS may be an Internet Protocol (IP) router. The CS may be an IP router with Ethernet switch capability. The CS may be a host capable of communicating with other hosts using one or more OSI layer two protocols, such as Ethernet, High-Speed Packet Access (HSPA), HSPA+, Long Term Evolution (LTE), WiMax, GPRS, EDGE, GSM, CDMA, WiFi, CDMA2000, WCDMA, TD-SCDMA, BLUETOOTH, and WiBRO.

FIG. 2 is a flow chart illustrating how communication system reduces broadcast and multicast packets according to one of the embodiments of the present invention. When a communication system (CS) receives a layer two packet (Received L2 Packet) at step 200 through a network connection, which may be implemented by different network connection technologies, including wireless, wire and optical fiber, the CS determines whether transmission type of the Received L2 Packet is broadcast, multicast or unicast at step 201. According to one of the embodiments of present invention, the CS determines the transmission type by checking the destination address of the Received L2 Packet. In Ethernet network, media access control address (MAC address) the multicast and broadcast addresses are FF:FF:FF:FF:FF:FF in hexadecimal. As it is possible that the Received L2 Packet is encapsulated in one or more layer three packets (Received L3 Packets), the CS may need to decapsulate the Received L3 Packet to retrieve Received L2 Packet at step 201. Hosts communicating with each other using IP may use IGMP to determine the multicast address.

CS determines whether to send another layer two packet (CSL2 Packet) at step 202. According to one of the embodiments of present invention, CS sends CSL2 Packet if transmission type of Received L2 Packet is unicast. According to one of the embodiments of present invention, CS does not send CSL2 Packet if transmission type of Received L2 Packet is broadcast or multicast. According to one of the embodiments of present invention, CS sends a broadcast or multicast CSL2 Packet if transmission type of Received L2 Packet is unicast and the destination address of the Received L2 Packet is a pre-determined address. According to one of the embodiments of present invention, CS sends a broadcast CSL2 Packet if transmission type of Received L2 Packet is unicast and the Received L3 Packets is received at a pre-defined port. According to one of the embodiments of present invention, the decision whether to send CSL2 Packet is based on one or more pre-defined rules (Pre-defined Rules).

CSL2 Packet is based on the Received L2 Packet. The content carried by the CSL2 Packet is from the content carried by the Received L2 Packet.

The destination address of CSL2 Packet is determined at step 204. According to one of the embodiments of present invention, when the transmission type of CSL2 Packet is broadcast, the destination address is a broadcast address, such as FF:FF:FF:FF:FF:FF used in Ethernet. When the transmission type of CSL2 Packet is unicast, the destination address is the layer two address of the receiver of CSL2 packet, such as a Media Access Control (MAC) address of the receiver of CSL2 Packet in Ethernet protocol. According to one of the embodiments of present invention, the destination address is determined according to Pre-defined Rules.

The number of combinations of the pre-defined rules may be numerous. Network administrators and/or communication system manufacturers may configure the pre-defined rules according to their needs and network environments.

Pre-defined Rules may be inputted to the CS manually by the CS administrator, retrieved from a server either locally or remotely or pre-determined by the manufacturer of the CS. The Pre-defined Rules are stored in a machine-readable medium which may be implemented in the CS or another device.

Scenarios

The implementations consider at least the next eight scenarios. The first four scenarios are associated with the CS implementing the present invention being Tunnel Termination Gateway 104 which is connected to private networks 105 and Internet 103. Tunnel Termination Gateway 104 may be implemented by using a router, a server, a switch or any communication system that is capable of terminating layer two tunnel. Tunnel Termination Gateway 104 decides whether to send CSL2 Packet and determines the destination address according to the following four scenarios and may be implemented in Pre-defined Rules.

The second four scenarios are associated with the CS implementing the present invention being an AP, such as AP 101 and AP 102, and connected to hosts such as computing devices 111, 112, 113 and 114 and Internet 103. AP 101 and AP 102 may also be implemented by using a router, a server, a switch or any communication system that is capable of communicating wirelessly and terminating layer two tunnel. AP 101 or AP 102 decides whether to send CSL2 Packet and determines the destination address according to the next four scenarios and may be implemented according to a set of Pre-defined Rules.

The first scenario is that the Received L2 Packet is received by Tunnel Termination Gateway 104 through Internet 103 with a pre-defined layer two broadcast destination address or a multicast destination address. According to one of the embodiments of present invention, as the destination address of Received L2 Packet is a pre-defined broadcast or multicast destination address; Tunnel Termination Gateway 104 determines whether the Received L2 Packet is intended for broadcast or multicast to private networks 105. Therefore, Tunnel Termination Gateway 104 decides that a CSL2 Packet is to be sent with broadcast transmission type or multicast transmission type to the private network at step 202 and the destination address is a broadcast or multicast layer two address at step 204. The pre-defined layer two broadcast destination or multicast address of the Received L2 Packet may be any layer two address, such as FF:FF:FF:FF:FF:FF for Ethernet, as long as Tunnel Termination Gateway 104 is able to recognize the use of the specific layer two address is for broadcast or multicast purpose. When the Received L2 Packet is originated from one of the computing devices 111-114, the Received L2 Packet is the same as the Computer Layer Two Packet mentioned earlier.

FIG. 3A illustrates the relationship among level 2 and level 3 packets received and sent by Tunnel Termination Gateway 104 when the Received L2 Packet 301 is sent by an AP and received by Tunnel Terminal Gateway 104. Here, the Received L2 Packet 301 is a Computer Layer Two Packet, which encapsulates Computer Layer Three Packet and is encapsulated in AP Layer Three Packets 303. Computer Layer Three Packet is the layer three packet sent by a computing device, one of computing devices 111-114. Tunnel Termination Gateway 104 decapsulates AP Layer Three Packets 303 to retrieve Computer Layer Two Packet, which now becomes CSL2 Packet because Tunnel Termination Gateway 104 sends CSL2 Packet 302 to Private Networks 104. Computer Layer Three Packet remains encapsulated in the CSL2 Packet.

According to one of the embodiments of present invention, when the pre-defined layer two broadcast or multicast destination address is the layer two address of Tunnel Termination Gateway 104, Tunnel Terminal Gateway 104 checks the port number of the Computer Layer Three Packet, which is encapsulated in the Received L2 Packet, to determine whether the Received L2 Packet is for broadcast or multicast purpose.

The second scenario is that the Received L2 Packet is received by Tunnel Termination Gateway 104 through Internet 103 with a non-pre-defined layer two broadcast or multicast destination address. According to one of the embodiments of present invention, as the destination address of Received L2 Packet is not a pre-defined broadcast or multicast destination address, Tunnel Termination Gateway 104 may determine that the Received L2 Packet is intended for unicast to a specific layer two address in the private networks 105. Therefore, Tunnel Termination Gateway 104 decides that a CSL2 Packet is to be sent with unicast transmission type to a device, such as Gateway 106 and Server 115, through private network at step 202 and the destination address is a unicast layer two address at step 204. When the Received L2 Packet is originated from one of the computing devices 111-114, the Received L2 Packet is the same as the Computer Layer Two Packets mentioned earlier.

It should be noted when Tunnel Termination Gateway 104 receives the Received L2 Packet through Internet 103, the Received L2 Packet is encapsulated in AP Layer Three Packets. Tunnel Termination Gateway 104 may decapsulate the AP Layer Three Packets to retrieve the Received L2 Packet. According to one of the embodiments of present invention, the decapsulation process is conducted by another communication system that terminates the layer two tunnels established with AP 101 and AP 102. In such case, the Received L2 Packet is received from that communication system.

Regardless of the transmission type of CSL2 Packet, when Tunnel Termination Gateway 104 sends CSL2 Packet through private networks 105, Tunnel Termination Gateway 104 need not encapsulate CSL2 Packet in one or more layer three packets at step 205 because private network 105 is a layer two network. Therefore, step 206 is then executed, instead of step 207.

The third scenario is that the Received L2 Packet is received by Tunnel Termination Gateway 104 through private network 105 with a pre-defined layer two broadcast or multicast destination address. According to one of the embodiments of present invention, as the destination address of Received L2 Packet is a pre-defined broadcast or multicast destination address, Tunnel Termination Gateway 104 may determine that the Received L2 Packet is intended for broadcasting or multicasting to AP 101-102 and computing devices 111-114 through Internet 103. Therefore, Tunnel Termination Gateway 104 decides that no CSL2 Packet is sent at step 202 in order to reduce network packets and/or conserve wireless spectrum. The operation stops at step 203.

FIG. 3B illustrates the relationship among level 2 and level 3 packets received and sent by Tunnel Termination Gateway 104 when the Received L2 Packet 301 is received through Private Networks 104. Received L2 Packet 301 received by Tunnel Terminal Gateway 104 is a Gateway Layer Two Packet, which encapsulates Internet Packet. Internet Packet is a layer three packet received by Gateway 106 and intended to be sent to one of or all computing devices 111-114. CSL2 Packet 302 is encapsulated in Tunnel Layer Three Packet 304 and same as Gateway Layer Two Packet. Tunnel Termination Gateway 104 sends Tunnel Layer Three Packet 304 to one of the AP if the transmission type is unicast or to all AP if the transmission type is broadcast or multicast.

The fourth scenario is that the Received L2 Packet is received through private network 105 with a non-pre-defined layer two broadcast or multicast destination. According to one of the embodiments of present invention, as the destination address of Received L2 Packet is not a pre-defined layer two broadcast or multicast destination, Tunnel Termination Gateway 104 determines that the Received L2 Packet is intended for unicast to a specific layer two address belonging to one of computing devices 111-114 reachable through Internet 103. Therefore, Tunnel Termination Gateway decides that a CSL2 Packet is to be sent with unicast transmission type through Internet 103 at step 202 and the destination address is a specific layer two address at step 204 of one of computing devices 111-114 and AP 101-102. The CSL2 Packet is determined to be encapsulated in one or more layer three packets at step 205 and the one or more layer three packets, which are the same as Tunnelled Layer Three Packets, are sent at step 207.

It should be noted that when the Received L2 Packet is received from Gateway 104, Received L2 Packet may have already encapsulated Internet Packets. In such case, Received L2 Packet is the same as Gateway Layer Two Packet and Tunnelled Layer Three Packet encapsulates CSL2 Packet.

The fifth scenario is that the Received L2 Packet is received by AP 101 from a directly connected host, such as computing device 113, with a pre-defined layer two broadcast or multicast destination address. According to one of the embodiments of present invention, as the destination address of Received L2 Packet is a pre-defined broadcast or multicast destination address, AP 101 is able to determine that the Received L2 Packet is intended for broadcast or multicast respectively. Therefore, it is decided that a CSL2 Packet is sent to Tunnel Termination Gateway 104 with broadcast or multicast transmission type at step 202 and the destination address may be a broadcast layer two address or the layer two address of Tunnel Termination Gateway 104 at step 204. As the Tunnel Termination Gateway 104 is only reachable through Internet 103, AP 102 has to send the CSL2 Packet through Internet 103. AP 102 at step 205 and step 207 encapsulates and sends the CSL2 Packet in one or more layer three packets, which are AP Layer Three Packet, to Tunnel Termination Gateway 104 through Internet 103 using the layer three address of Tunnel Termination Gateway 104.

FIG. 3C illustrates the relationship among level 2 and level 3 packets received and sent by an AP when the Received L2 Packet 301 is received from one of the computing devices 111-114. Received L2 Packet 301 received by the AP is a Computer Layer Three Packet. The AP retrieves the Computer Layer Three Packet from Received L2 Packet 301 and encapsulates the Computer Layer Three Packet in CSL2 Packet 302, which is encapsulated in AP Layer Three Packet 303. The AP then sends AP Layer Three Packet 303 to Tunnel Termination Gateway 104.

The port number of AP Layer Three Packet may be set to a pre-defined port number to inform Tunnel Termination Gateway 104 that the AP Layer Three Packet encapsulates a CSL2 Packet intended for broadcasting. Depending on the preferences of the manufacturer and/or the administrator of AP 101, AP 101 may or may not broadcast the Received L2 Packet to other hosts directly connected. If AP 101 does not broadcast the CSL2 Packet to other hosts directly connected, network packets may be reduced. If AP 101 decides to broadcast the CSL2 Packet to other hosts directly connected at step 205, the CSL2 Packet is then sent to the hosts at step 207.

The sixth scenario is that the Received L2 Packet is received by AP 101 from a directly connected host, such as computing device 111, with a non-pre-defined layer two broadcast or multicast destination address. According to one of the embodiments of present invention, as the destination address of Received L2 Packet is not a pre-defined broadcast destination address, AP 101 may determine that the Received L2 Packet is intended for unicast to a specific layer two address, which may belong to another device directly connecting to AP 101, such as computing device 112 or another device in the same layer two network reachable through Internet 103. Therefore, AP 101 decides that a CSL2 Packet is to be sent at step 202 and also decides that the transmission type is unicast at step 204. The layer two destination address of the CSL2 Packet is the destination address of the Received L2 Packet. If AP 101 may send the destination address of the CSL2 Packet without passing through Internet 103, such as computing device 112, AP 101 may send the CSL2 Packet to computing device 112 with layer three encapsulation. If AP 101 has to send the CSL2 Packet through Internet 103, AP 101 at step 205 and step 207 encapsulates and sends the CSL2 Packet in one or more layer three packets, which are AP Layer Three Packets, to Tunnel Termination Gateway 104 through Internet 103 using the layer three address of Tunnel Termination Gateway 104.

The seventh scenario is that the Received L2 Packet is received by AP 101 through Internet 103 with a pre-defined layer two broadcast destination address. Using FIG. 1 for illustrative purpose, when the destination address of Received L2 Packet is a pre-defined broadcast destination address, the Received L2 Packet is intended for broadcasting to computing devices 111 and 112. Depending on the preferences of the manufacturer and/or the administrator of AP 101, AP 101 may or may not broadcast the Received L2 Packet to other computing devices 111 and 112 at step 202. If AP 101 does not broadcast the CSL2 Packet to hosts directly connected, network packets may be reduced and the process stops at step 203. If AP 101 decides to broadcast the CSL2 Packet to other hosts directly connected at step 202, the destination address of CSL2 Packet is the pre-defined layer two broadcast destination, such as MAC Address FF:FF:FF:FF:FF:FF in Ethernet at step 204. As computing devices 111 and 112 are in the same layer two network, there is no layer three encapsulation at step 205 and the CSL2 Packet is sent at step 206.

FIG. 3D illustrates the relationship among level 2 and level 3 packets received and sent by an AP when the Received L2 Packet 301 is sent by Tunnel Termination Gateway 104 and received by one of AP 101 or 102. Here, the Received L2 Packet 301 is a Gateway Layer Two Packet, which encapsulates Internet Packet and is encapsulated in Tunnel Layer Three Packets 304. The AP decapsulates Tunnel Layer Three Packet 304 to retrieve Gateway Layer Two Packet. Using FIG. 1 for illustrative purpose, the AP sends CSL2 Packet 302, which is the Gateway Layer Two Packet, to one of the computing devices 111-114 if the transmission type is unicast or to all computing devices 111-114 if the transmission type is broadcast.

The eighth scenario is that the Received L2 Packet is received by AP 101 through Internet 103 with a non-pre-defined layer two broadcast destination address. According to one of the embodiments of present invention, as the destination address of Received L2 Packet is not a pre-defined broadcast destination address, the Received L2 Packet is intended for unicast to a specific computing device directly connected, such as one of computing devices 111 and 112. Therefore, AP 101 decides that a CSL2 Packet is to be sent at step 202 and also decides that the transmission type is unicast at step 204. The layer two destination address of the CSL2 Packet is the destination address of the Received L2 Packet. AP 101 sends the CSL2 Packet to either computing device 111 or 112 at step 206 without layer three encapsulation at step 205. As the Received L2 Packet is received through Internet 103, it is encapsulated in one or more layer three packets, which are Tunnel Layer Three Packets originated from Tunnel Termination Gateway 104. AP 101 has to decapsulate Tunnel Layer Three Packets in order to retrieve the Received L2 Packet.

It should be noted that the payload contained in Received L2 Packet should be the same as the payload contained in CSL2 Packet but the layer two destination address of Received L2 Packet may be different from of CSL2 Packet. This is because the CS, which may be an AP or Tunnel Termination Gateway, may change the layer two destination address in order to convert a layer two broadcast or multicast destination address to a layer two unicast destination address.

According to one of the embodiments of present invention, instead of relying on the layer two destination address of the Received L2 Packet or relying on port number of the layer three packets encapsulating the Received L2 Packet to determine whether the Received L2 Packet is intended for broadcast or multicast, the CS examines the information stored in the payload of the Received L2 Packet in order to make the decision.

According to one of the embodiments of present invention, the Received L2 Packet encapsulates an IP Address Resolution Protocol (ARP) packet, which may be a probe, announcement or reply packet. If the ARP packet is a probe or announcement packet, the transmission type of the Received L2 Packet is broadcast or multicast. Then depending on the origin of the Received L2 Packet, such as from private networks 105 or from one of the computing devices 111-114, the CS, such as AP 101, AP 102 or Tunnel Termination Gateway 104 may determine whether to broadcast or multicast a corresponding CSL2 Packet. It is apparent to a skilled person in the art how to recognize if the Received L2 Packet encapsulates an IP ARP packet and the type of ARP packet.

According to one of the embodiments of present invention, when Received L2 Packet is an ARP reply packet, the CS, such as AP 101, AP 102 or Tunnel Termination Gateway 104, caches the IP address and MAC address pair of the ARP reply packet. The transmission type of the Received L2 Packet may be unicast or broadcast. When the CS receives another Received L2 Packet, which may be unicast, broadcast or multicast, containing an ARP probe packet later, CS then responds to the sender of the ARP probe packet by sending a CSL2 Packet with the cached IP address and MAC address pair. Therefore, the CS is acting like an ARP cache. It is apparent to a skilled person in the art how to implement an ARP cache. A computer storage medium may be used as a cache for storing the cached IP address and MAC address pair.

According to one of the embodiments of present invention, the Received L2 Packet encapsulates an IP Dynamic Host Configuration Protocol (DHCP) packet, which may be a discovery, offer, request, acknowledgement, information or releasing packet. If the DHCP packet is a discovery or request packet, the transmission type of the packet is broadcast. Then, depending on the origin of the Received L2 Packet, such as from private networks 105 or from one of the computing devices 111-114, the CS, such as Tunnel Termination Gateway 104. AP 101 or AP 102, then determines whether to broadcast or multicast a corresponding CSL2 Packet. It is apparent to a skilled person in the art how to recognize if the Received L2 Packet encapsulates an IP DHCP packet and the type of DHCP packet.

According to one of the embodiments of present invention, when transmission type of Received L2 Packet is broadcast or multicast and transmission type of CSL2 Packet is unicast, the layer two destination address in the case of Ethernet is changed from broadcast address FF:FF:FF:FF:FF:FF or a multicast address to a layer two unicast address. However, if the CS is an AP, such as one of AP 101-102, the AP needs to learn the layer two destination address, which is the layer two address of Tunnel Termination Gateway 104. The layer two address of Tunnel Termination Gateway 104 may be inputted by network administrator, received by querying another communication system whose address is pre-configured, or by learnt from the response after sending a pre-defined layer three packet. If a pre-defined layer three packet is used, AP may then learn the destination address from the reply of the pre-defined layer three packet.

According to one of the embodiments of present invention, layer three packets exchanged between Tunnel Termination Gateway 104 and APs are used to determine the destination address of CSL2 Packet when the transmission type of Received L2 Packet is broadcast or multicast. An AP and Tunnel Termination Gateway 104 both listen to the same specific User Data Protocol (UDP) port. The AP first sends a UDP packet to the specific UDP port of the Tunnel Termination Gateway 104, whose IP address is learnt by the AP from DHCP packets or pre-determined configuration. Tunnel Termination Gateway 104 intercepts any UDP packets arriving at the specific UDP port and checks the payload of the UDP packets. If the payload matches a pre-defined format or content, Tunnel Termination Gateway 104 is then able to recognize the layer two address of the AP, and may send a second UDP packet to the same specific UDP port of AP for confirmation. When AP received the second UDP packet, it also verifies whether the payload of the second UDP packet matches a pre-defined format or content and, if so, the AP stores the layer two source address of the second UDP packet, such as the MAC address of the second UDP packet. From then on, until further reset or change of network conditions, AP sets the destination address of CSL2 packet to the layer two source address of the second UDP packet when the transmission type of Received L2 Packet is broadcast or multicast.

According to one of the embodiments of present invention, the communication system, such as AP 101, AP 102 and Tunnel Termination Gateway 104 may be composed of two communication systems. The first communication system is responsible for establishing layer two tunnels by using layer three communication technologies, such as a L2TP network server. The second communication system is responsible for determine whether to send CSL2 packet, the transmission type of the CSL2 packets and the destination address of CSL2 packets.

Communication System

FIG. 4 illustrates one of the embodiments of present invention of a communication system according to the present invention described. The communication system 401 comprises a processor unit(s) 402, a data storage 405, at least one LAN interface 402, and at least one WAN interface 403, for use with other network apparatus such as WiMAX routers, Ethernet switches, IP routers and other packet network devices, network management and provisioning systems, local PCs, etc. Processor unit(s) 402 couples to data storage 405, LAN interface 402, and WAN interface 403 respectively. Other components which may be utilized within the network device 401 include amplifiers, board level electronic components, as well as media processors and other specialized SoC or ASIC devices. Support for various processing layers and protocols (e.g., 802.3, DOCSIS MAC, DHCP, SNMP, H.323/RTP/RTCP, VoIP, SIP, etc.) may also be provided as required.

Communication system 401 may take any number of physical forms, comprising for example one of a plurality of discrete modules or cards within a larger network edge or hub device of the type well known in the art and may also comprise firmware, either alone or in combination with other hardware/software components. Alternatively, Communication system 401 may be a stand-alone device or module disposed at other computing device or network device, and may even include its own RF front end (e.g., modulators, encryptors, etc.) or optical interface so as to interface directly with other computing devices and network devices. Numerous other configurations may be used. Communication system 401 may also be integrated with other types of components (such as mobile base stations, satellite transceivers, video set-top box, encoders/decoders, etc.) and form factors if desired.

Processing unit 404 may be implemented by using one or more central processing units, network processors, microprocessors, micro-controllers, FPGAs, ASICs or any device capable of performing instructions to perform the basic arithmetical, logical, and input/output operations of the system.

Computer storage medium 405 may be implemented by using at least one DRAM, SDRAM, Flash RAM, optical memory, magnetic memory, hard disk, and/or any computer readable media that are able to provide data storage capability. Computer storage medium 405 may be used to provide instructions to processing units 402 and to provide data storage to store cache, identifiers, conditions, thresholds, network performance statistics, web pages, messages and other data to facilitate the operation of the communication system 401.

When communication system 401 receives a Received L2 Packet through a network connection in either LAN interface 402 or WAN interface 403, processing unit 404 determines whether transmission type of the Received L2 Packet is broadcast, multicast or unicast. The network connection may be implemented by different network connection technologies, including wireless, wire and optical fiber. According to one of the embodiments of present invention, the processing unit 404 determines the transmission type by checking the destination address of the Received L2 Packet. As it is possible that the Received L2 Packet is encapsulated in one or more Received L3 Packets, processing unit 404 may need to decapsulate the Received L3 Packet to retrieve Received L2 Packet. Hosts communicating by using IP may use IGMP to determine the multicast address.

Processing unit 404 determines whether to send a CSL2 Packet. If processing unit 404 determines to send a CSL2 packet, the CSL2 packet is sent through WAN interface 403 if the Received L2 Packet is received from LAN interface 402. On the other hand, if processing unit 404 determines to send a CSL2 packet, the CSL2 packet is sent through LAN interface 402 if the Received L2 Packet is received from WAN interface 403. CSL2 According to one of the embodiments of present invention, processing unit 404 decides to send CSL2 Packet if transmission type of Received L2 Packet is unicast. According to one of the embodiments of present invention, processing unit 404 decides not to send CSL2 Packet if transmission type of Received L2 Packet is broadcast or multicast. According to one of the embodiments of present invention, processing unit 404 decides to send a broadcast or multicast CSL2 Packet if transmission type of Received L2 Packet is unicast and the destination address of the Received L2 Packet is a pre-determined address. According to one of the embodiments of present invention, processing unit 404 decides to send a broadcast CSL2 Packet if transmission type of Received L2 Packet is unicast and the Received L3 Packets is received at a pre-defined port. According to one of the embodiments of present invention, the decision whether to send CSL2 Packet is based on one or more Pre-defined Rules.

Computer storage medium 405 may be used to store the content carried by Received L2 Packet. In one variant, once the corresponding CSL2 Packet is sent, the content carried by the Received L2 packet that is stored in computer storage medium 405 is then removed in order to release data storage space.

The destination address of CSL2 Packet is determined by processing unit 404. According to one of the embodiments of present invention, the destination address is determined by process unit 404 according to Pre-defined Rules. The Pre-defined Rules are stored in computer storage medium 405.

Referring to the eight scenarios described earlier, processing unit 404 of a communication system, such as Tunnel Termination Gateway 104, AP 101 and AP 102 performs the function of determining whether a Received L2 Packet is intended for broadcast, multicast or unicast, determining the transmission type of a CSL2 Packet, the destination address of the CSL2 Packet, establishing VPN, terminating VPN, encapsulating a layer two packets in at least one layer three packet, decapsulating a layer two packet from at least one layer three packet, and other processing functions.

According to one of the embodiments of present invention, the communication system, such as AP 101, AP 102 and Tunnel Termination Gateway 104 may be composed of at least one layer three router and at least one layer two switch. The at least one layer three router is responsible for establishing layer two tunnels by using layer three communication technologies, such as a L2TP network server. The at least one layer two switch is responsible for determining whether to send CSL2 packet, the transmission type of the CSL2 packets and the destination address of CSL2 packets. Each of the layer three router and layer two switch has its own processing unit, computer storage medium, LAN interface, WAN interface to carry out the functions of communication system 401. The at least one layer three router is used to connect to an external network, such as interconnected network or the Internet. The LAN interface of the at least one layer three router is connected to one of the ports of the at least one layer two switch. Another one of the ports of the at least one layer two switch is connected to the private network. It is apparent to a skilled person in the art how to implement at least one layer three router and at least one layer two switch for carrying out the functions of communication system 401.

According to one of the embodiments of present invention, at least one LAN interface of communication system 401 is an 802.11 interface that allows hosts to connect to the communications system using IEEE 802.11 protocol, including 802.11a, 802.11b, 802.11g, 802.11n, 802.11ac, and 802.11ad; at least one WAN interface is an 802.16 interface that allows communication system 401 to connect to inter-network or the Internet through IEEE 802.16 protocol. In one variant, the WiMAX modem is embedded inside communication system 401 and therefore WAN interface may directly connect with an antenna. In one variant, an IEEE 802.11 modem is embedded inside communication system 401 and therefore LAN interface may directly connect with at least one antenna. In one variant, the an IEEE 802.16 modem is embedded inside communication system 401 and therefore WAN interface may directly connect with at least one antenna.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 illustrates a network environment where communication systems and hosts, such as client computers 111, 112, 113 and 114 communicate to wide area networks (WANs) or the Internet directly.

FIG. 2 is a flow chart illustrating how communication system reduces broadcast and multicast packets according to one of the embodiments of the present invention.

FIG. 3A illustrates the relationship among level 2 and level 3 packets received and sent by Tunnel Termination Gateway 104 when the Received L2 Packet 301 is sent by an AP and received by Tunnel Terminal Gateway 104.

FIG. 3B illustrates the relationship among level 2 and level 3 packets received and sent by Tunnel Termination Gateway 104 when the Received L2 Packet 301 is received through Private Networks 104.

FIG. 3C illustrates the relationship among level 2 and level 3 packets received and sent by an AP when the Received L2 Packet 301 is received from one of the computing devices 111-114.

FIG. 3D illustrates the relationship among level 2 and level 3 packets received and sent by an AP when the Received L2 Packet 301 is sent by Tunnel Termination Gateway 104 and received by one of AP 101 or 102.

FIG. 4 illustrates one of the embodiments of present invention of a communication system according to the present invention described. 

1. A method of operating a communication system, comprising the steps of: receiving a first Open Systems Interconnection (OSI) layer two packet from a first network interface; determining transmission type of the first OSI layer two packet; determining whether to send a second OSI layer two packet according to the transmission type, origin and destination of the first OSI layer two packet, wherein content of the second OSI layer two packet is based on content of the first OSI layer two packet; determining destination address and transmission type of the second OSI layer two packet when determined to send the second OSI layer two packet; and sending the second OSI layer two packet through a second network interface when determined to send the second OSI layer two packet; wherein when the first OSI layer two packet is encapsulated in at least one layer three packet, the second OSI layer two packet is not encapsulated in any OSI layer three packet; and wherein when the first OSI layer two packet is not encapsulated in any Open Systems Interconnection (OSI) layer three packet, the second OSI layer two packet is encapsulated in at least one OSI layer three packet.
 2. The method of claim 1, wherein content of the second OSI layer two packet is retrieved from a computer storage medium.
 3. The method of claim 1, wherein the first layer two packet encapsulates an Internet Protocol (IP) Address Resolution Protocol (ARP) packet.
 4. The method of claim 3, further comprising storing the IP ARP packet contained in the first OSI layer two packet, wherein transmission type of the first OSI layer two packet is unicast and wherein the first OSI layer two packet is an ARP reply.
 5. The method of claim 1, wherein the first layer two packet encapsulates an IP Dynamic Host Configuration Protocol (DHCP) packet.
 6. The method of claim 1, wherein the first layer two packet and the second OSI layer two packet comprise with one or more of the following communication standards: Ethernet, High-Speed Packet Access (HSPA), HSPA+, Long Term Evolution (LTE), WiMax, GPRS, EDGE, GSM, CDMA, WiFi, CDMA2000, WCDMA, TD-SCDMA, BLUETOOTH, and WiBRO.
 7. The method of claim 1, wherein the communication system is a wireless access point.
 8. The method of claim 1, wherein the any layer three packets and the at least one OSI layer three packet are IP packets.
 9. The method of claim 8, wherein the destination address of the second OSI layer two packet is determined through exchange of User Data Protocol (UDP) packets at a pre-defined port number.
 10. The method of claim 8, wherein when transmission type of the second OSI layer two packet is determined to be broadcast or multicast and second OSI layer two packet is encapsulated in the at least one IP packet, port number of the at least one IP packet is set to a pre-defined value for identifying the transmission type of the second OSI layer two packet is broadcast or multicast.
 11. The method of claim 1, wherein when the first OSI layer two packet is encapsulated in at least one OSI layer three packet, the first OSI layer two packet is received from a virtual private network (VPN), and wherein when the second OSI layer two packet is encapsulated in at least one OSI layer three packet, the second OSI layer two packet is sent through a VPN.
 12. A communication system comprising at least two network interfaces, at least one procession unit, and a computer storage medium comprising program instructions executable by the at least one procession unit to perform the operation of: receiving a first OSI layer two packet from a first network interface; determining transmission type of the first OSI layer two packet; determining whether to send a second OSI layer two packet according to the transmission type, origin and destination of the first OSI layer two packet, wherein content of the second OSI layer two packet is based on content of the first OSI layer two packet; determining destination address and transmission type of the second OSI layer two packet when determined to send the second OSI layer two packet; and sending the second OSI layer two packet through a second network interface when determined to send the second OSI layer two packet; wherein when the first OSI layer two packet is encapsulated in at least one OSI layer three packet, the second OSI layer two packet is not encapsulated in any OSI layer three packet; and wherein when the first OSI layer two packet is not encapsulated in any OSI layer three packet, the second OSI layer two packet is encapsulated in at least one OSI layer three packet; wherein the at least one procession unit coupled to the at least two network interfaces and the computer storage medium.
 13. The communication system of claim 12, wherein content of the second OSI layer two packet is retrieved from the computer storage medium.
 14. The communication system of claim 12, wherein the first OSI layer two packet encapsulates an IP ARP packet.
 15. The communication system of claim 14, wherein program instructions executable by the at least one procession unit to further perform the operation of storing the IP ARP packet contained in the first OSI layer two packet, wherein transmission type of the first OSI layer two packet is unicast and wherein the first OSI layer two packet is an ARP reply.
 16. The communication system of claim 12, wherein the first OSI layer two packet encapsulates an IP DHCP packet.
 17. The communication system of claim 12, wherein the first OSI layer two packet and the second OSI layer two packet comprise with one or more of the following communication standards: Ethernet, High-Speed Packet Access (HSPA), HSPA+, Long Term Evolution (LTE), WiMax, GPRS, EDGE, GSM, CDMA, WiFi, CDMA2000, WCDMA, TD-SCDMA, BLUETOOTH, and WiBRO.
 18. The communication system of claim 12, wherein the communication system is a wireless access point.
 19. The communication system of claim 12, wherein the any OSI layer three packets and the at least one OSI layer three packet are IP packets.
 20. The communication system of claim 19, wherein the destination address of the second OSI layer two packet is determined through exchange of UDP packets at a pre-defined port number.
 21. The communication system of claim 19, wherein when transmission type of the second OSI layer two packet is determined to be broadcast or multicast and second OSI layer two packet is encapsulated in at least one IP packet, port number of the at least one IP packet is set to a pre-defined value for identifying the transmission type of the second OSI layer two packet is broadcast or multicast.
 22. The communication system of claim 12, wherein when the first OSI layer two packet is encapsulated in at least one OSI layer three packet, the first OSI layer two packet is received from a virtual private network (VPN) and wherein when the second OSI layer two packet is encapsulated in at least one OSI layer three packet, the second OSI layer two packet is sent through a VPN.
 23. The communication system of claim 22, wherein the communication system is comprises at least one OSI layer three router capable of terminating VPN and at least one OSI layer two switch capable of receiving and forwarding lawyer two packets.
 24. The communication system of claim 22, wherein one of the at least two network interface further comprises an 802.11 interface and another one of the at least two network interface further comprises 802.16 interface. 